The present invention relates to an insulating material for forming a main insulation for windings of electrical machines, windings for electrical rotating machines using the insulating material, and a method for manufacturing the windings.
JP-A-63-110929 (1988) discloses a method of forming insulating film for electrical windings used in electrical rotating machines by applying an insulating material to a conductor bundle, which comprises a mica layer, a reinforcement layer, a filler layer containing fillers having a high thermal conductivity therein, and each of the layers contains thermosetting resin.
The insulating material is wound around the wound conductor bundle, and the insulating film for windings of electrical machines is formed by curing the resin in the insulating material under heating and pressurizing. The windings for electrical machines is manufactured by the steps comprising wrapping the conductor with the insulating material which comprises the above mica layer, reinforcement layer, and filler layer; impregnating thermosetting resin composition containing fine divided inorganic filler into the insulating layer; and curing the resin composition by heating under pressurizing.
Furthermore, a method is disclosed, wherein a thermosetting resin composition containing fillers is impregnated into or applied onto the mica foil before wrapping the conductor with the mica layer containing the reinforcement layer.
JP-A-55-53802 (1980) discloses an insulating material, wherein a synthetic fiber fibrid and a high heat conductive inorganic powder are mixed into bonded mica sheet, and a thermosetting resin is impregnated therein. The publication discloses an insulating sheet, which is formed by adhering glass cloth to the mica paper with epoxy resin.